Synthesis, characterisation and X-ray structures of yttrium, barium and copper(II) β-ketoesterate complexes

β-Ketoesterates derivatives M(mpa)x (M=Y, Ba, Cu; mpaH=methylpivaloylacetate; x=2 or 3) were prepared by ligand exchange reactions starting from methoxides (M=Ba, Cu) or from tristrimethylsilylamide (M=Y) derivatives. Decomplexation of the oligomeric and non-volatile Ba and Y species was achieved by various Lewis bases. Adducts Y(mpa)3L [L=tmeda (N,N,N′,N′-tetramethylethane-1,2-diamine), bipy (2,2′-bipyridine)] and Ba(mpa)2L [L=diglyme, 18-crown-6 ether; pmdta=N,N,N′,N′,N″-pentamethylethylenetriamine] and [Ba(mpa)2(tmedta)2] were obtained. All compounds were synthesised in high yield and characterised by elemental analyses, 1H NMR, FT-IR and TGA. The structures of [Ba(mpa)2(tmeda)2] and [Y(mpa)3(bipy)] were established by single crystal X-ray diffraction. The metals are eight-coordinated with a slightly distorted square antiprismatic surrounding. The yttrium complexes sublime as adducts. The barium complexes, by contrast, are dissociated in the vapour phase. Better solubility properties in polar and non-polar with respect to the 2,2,6,6-tetramethylheptane-3,5-dionates analogues were observed especially for the copper species. These compounds are thus potential metal-oxide precursors for liquid injection MOCVD using solvents such as hexane or diglyme.